Trueperellapyogenes are environmental pathogens that typically cause an acute, purulent form of mastitis that is sometimes referred to as “summer mastitis.” Trueperellapyogenes are Gram-positive bacteria that can appear like coccobacilli — an intermediate between cocci and bacilli. When plated on blood agar, scant to no growth is visible at 24 hours. However, at 48 hours, tiny, pinpoint, smooth, whitish colonies develop and are surrounded by a narrow zone of hemolysis.

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